The present invention relates to an appliance and kit for providing Herbst therapy as well as arch development to correct certain orthodontic misalignments including horizontal and vertical overbite and which includes a telescoping controlling rod arrangement.
Devices for treatment of orthodontic overbite have been proposed. In the early 1900""s, German orthodontic practitioners were well aware of the efficacy of incline planes to resolve overjets (overbite). As approximation of the teeth occurred, the inclined plane attached to the mandible contacted the inclined plane of the maxilla. As closure progressed, the lower jaw was forced into a protruded position as dictated by the inclines. Since correction of the overjet depended on constant protrusion of the mandible to effect cellular changes required to eventually result in the new and desired lower jaw position, it was necessary that patients so treated hold the teeth in constant contact. Holding teeth in the contact position required constriction of the muscles which protrude the lower jaw (pterygoids), whereas relaxation of those muscles resulted in the teeth losing contact and the lower jaw being allowed to retreat to its former position. With the jaw in its former position, no orthopedic cellular change and hence no permanent overjet correction would be realized.
Emil Herbst, in his early 1900 work xe2x80x9cZahnarztliche Orthopadiexe2x80x9d stated:
xe2x80x9cWhen many unsuccessful results through the use of inclined planes occurred, the reason was that many patients avoided the xe2x80x9cstressedxe2x80x9d position. Instead of holding their teeth closed or in contact with the inclined plane and allowing (or forcing) the muscles to function, it was more comfortable to hold the mouth open and avoid the strain . . . , that an incline plane can only be effective, when the teeth are truly in contact, and that on the other hand, many patients, especially uncooperative, lazy or unmotivated children, relax muscle pressure by holding the mouth open, I constructed a guide that would work against this relaxation (from holding the mouth open).xe2x80x9d
It is reasonable to conclude that if an inclined plane in one direction eliminates an overjet, an inclined plane in the opposite direction may create or exacerbate an overjet. By xe2x80x9cadverse inclined planexe2x80x9d what is meant is an inclined plane in the reverse direction. In the mouth there is a naturally occurring adverse inclined plane. That inclined plane is the relationship of the lower incisor tips in contact with the lingual surfaces of the upper incisors. FIG. 1 shows how increasing overbite results in increasing overjet or, as in the case of a mandible which has been forward-postured by an inclined plane-type of appliance, how the excess overbite and the contact between the lower incisor tips and the lingual surfaces of the upper incisors, results in retrusion of the mandible forcing it back into its original position thereby reversing those orthopedic changes previously derived.
Additionally overbite orthopedic correction appliances which have been employed have been subject to failure. Appliances for providing Herbst therapy are described in Mason, U.S. Pat. No. 4,551,095, Jones, U.S. Pat. No. 4,462,800 and Kumar, U.S. Pat. No. 5,183,338. The two common sources of failure are metal fatigue and inadequate weld or solder joints. All oral appliances are subject to the harsh dynamics associated with chewing, speech, and swallowing. During, for example, swallowing, there is motion associated with the lower jaw while the upper and lower jaws are closed together. Humans swallow in excess of 1000 times a day just to lubricate the pharyngeal mucosa. As a result of these oral dynamics, the metal parts of the appliance are stressed and flexed leading to metal fatigue and failure.
It is logical to conclude that by harmonizing the sizes of the components of an appliance, failure as a result of fatigue can be reduced. Further by eliminating or reducing welds, the incidents of failure can be reduced.
In Herbst devices it has been known to include a motion controlling rod coupling upper and lower components of the device such as disclosed in Cleary U.S. Pat. No. 5,964,588.
Some alignment devices have also used telescoping control rods such as disclosed in Northcutt U.S. Pat. No. 3,798,773 and Mihailowitsch U.S. Pat. No. 5,378,147.
Regarding telescoping rods, it would be beneficial to provide such a telescoping assembly. One reason is that the rod/tube assembly must remain connected when the patient opens their mouth very wide. If the rod can become disengaged from the tube when the patient yawns or opens their mouth wide, the patient can defeat the process by disengaging the rod/tube assemblies. Further, even a compliant patient may inadvertently disengage the assemblies frustrating use of the appliance. To negate disengagement, the rods are made long so as to extend through both ends of the tubes. This creates discomfort for the patient in that when the mouth closes the end of the rod may engage the mucosa covering the external ridge of the Coronoid process causing irritation as shown in FIG. 21.
Another reason for providing telescoping rod/tube assemblies would be beneficial is to make the appliance operator friendly. The technician installing the appliance need not spend time measuring and/or trimming rods and tubes to fit the variations in the installation.
There is set forth according to the present invention and appliance which provides for Herbst therapy and which permits opening and closing of the mandible as well as a degree of lateral mandible movement and which further contributes to the easy and programmed installation of the appliance.
Accordingly the present invention is directed to an orthodontic appliance to provide for Herbst therapy which includes a mandibular component including left and right buccal segments each including an arcuate foot adhered to the teeth over the occlusal embrasure between the cuspid and first bicuspid, each foot including a threaded bore in the facial surface thereof. A maxillary component including left and right bucco-occlusal segments each including a foot which is adhered to the teeth over the occlusal embrasure proximate the first molar and extending to the buccal side of the teeth, each bucco-occlusal segment having on said buccal side a threaded bore. Screws are adapted to be threadably and removably disposed in said threaded bores, each screw including a ball head
The appliance further includes telescoping rod and tube links having at the ends thereof sockets to receive said screw heads to pivotally mount the ends of rod and tube links to couple the mandibular and maxillary components to reposition the mandible. The links may further include an intermediate member to provide for the telescoping of the links to accommodate the opening and closing of the mouth. The ball and socket connections between the links and mandibular and maxillary components also provides for a degree of lateral displacement of the mandible to accommodate mastication and speech.
To couple the screw heads to the sockets, each socket may be defined by a cap and cup coupled together to trap the ball head in the socket recess and provide the ball and socket connection. The screws are then rotated to couple the links to the other components of the appliance.